This invention relates to an electronic circuit for producing a chime-like tone, and more particularly to an electronic chime.
Electrically operated aural signals are often used as warning signals or remainders. In contemporary automobiles, aural warnings are sounded when the car is started and the seatbelt/shoulder harness is not properly fastened or when the driver's door is open and the keys are in the ignition. Conventionally, a buzzer signal has been used to sound the aural reminder. While buzzers are inexpensive, reliable, and may be readily incorporated in automotive electrical systems, the buzzer sound is considered by many to be raucous and annoying.
In certain, more expensive automobiles, the buzzer has been replaced by an electromechanical chime having a chime bar which is struck by an electrically actuated hammer or plunger. While this electromechanical chime does produce a more pleasing tone, it suffers from many operating disadvantages compared with buzzer warning systems. First, known electromechanical chime systems are relatively large in size and heavy compared to a buzzer. Typically, these prior electromechanical chimes utilize a solenoid-operated hammer which when energized strikes a chime bar. It is necessary to provide a resonance chamber for the chime bar. It has been found that operation of this solenoid-operated hammer is sensitive to its orientation or position. If, for example, an automobile in which the electromechanical chime is installed is parked on an incline, the hammer may not properly sound the chime. If a multi-tone chime is desired, a separate chime bar, hammer, and resonance chamber is required for each desired tone. Still further, these prior electromechanical chimes incorporated movable parts (e.g., the hammer) which would, on occasion, stick or otherwise malfunction.
In recent years, several electronic chime circuits have become known. However, for the most part, they have either been overly complicated (and therefore expensive) or they have not produced a pleasing chime-like tone. Reference may be made to such U.S. Pat. Nos. as 3,653,040, 3,912,952, 3,971,016, 4,001,816 and 4,012,702 which disclose various prior art electronic chimes and other electronic aural devices in the same general field as the present invention.